How to remove a broken spark plug embedded deep down in the engine block
I would first remove the other spark plugs then turn crank manually until you feel the compression stroke of that one cylinder then rotate a 1/4 turn more, that should put that piston at about TDC.
If you look at the coil pack you can tell which cylinders are "paired"
So #3 cylinder and #4 cylinders are at TDC at the same time.
So just use your effected cylinders match to tell when it is at TDC.
The reason for TDC is because if you break the porcelain and it falls into the cylinder it will be easier to remove.
I have sprayed adhesive on a small diameter rope, thick coat so it stayed tacky, then inserted it into cylinder, move it around, then pull it out, repeat as you see fit.